Cell selection schemes for femtocell-to-femtocell handover deploying mobility prediction and downlink capacity monitoring in cognitive femtocell networks

Femtocell networks have been proposed for indoor communications as the extension of cellular networks for enhancing coverage performance. Because femtocells have small coverage radius (15 to 30 meters), femtocell users (FU) walking at low speed still make frequent femtocell-to-femtocell handover. When performing a femtocell-to-femtocell handover procedure, a cell selection scheme, which is used to select the target handover femtocell, should be able to reduce unnecessary handovers. The cell selection scheme should also support FU´s connection quality by not selecting an overloaded target femtocell. In this paper, we propose two new cell selection methods for femtocell-to-femtocell handover in which one is designed based on mobility prediction and another is based on femtocell capacity estimation. Simulation results show that each method provides different performance enhancement when comparing with the conventional RSS-based cell selection. It also shows that there is a trade-off between reducing unnecessary handover and avoiding overloaded femtocells which is the difficult and open challenge when designing an efficient cell selection scheme in future studies.